Update bot challenge page with UXWS suggestions

Why these changes are being introduced:

UXWS has requested changes to the copy in the
bot challenge page.

Relevant ticket(s):

- [USE-444](https://mitlibraries.atlassian.net/browse/USE-444)

How this addresses that need:

This implements the requested changes.

Side effects of this change:

None.

Author: jazairi

app/views/turnstile/show.html.erb

@@ -2,9 +2,9 @@
 
 <section class="turnstile-challenge">
   <div class="turnstile-challenge__inner">
-    <h1>Verify you're human</h1>
+    <h1 class="hd-4">Please verify below you are a human</h1>
     <p>
-      Please complete this verification to continue.
+      Sorry to require this extra step, but you’ve somehow landed on our bot challenge page and we need to be sure. Thanks!
     </p>
 
     <%= form_with url: turnstile_verify_path, method: :post, local: true do %>